Question about WD Black SN850X with Heatsink

I would simply recommend buying one without a heatsink! Cost is the same if not less + a little less to throw away. Would only buy one with heatsink if it was for a PS5. :D

No apart from the fact that the warranty is probably void! would order the one without alternatively.

Yes, you can use a small screwdriver (flat blade) to 'release' the upper part. The lower part sticks quite well to the circuit board and I have not yet tried to remove it. It is possible that this can be done with the aid of a hairdryer.